论文标题
Wenzel在液滴接触角的Young方程式何时应用？密度功能研究
When does Wenzel's extension of Young's equation for the contact angle of droplets apply? A density functional study
论文作者
论文摘要
他接触液滴在部分润湿条件下的表面上的角度，对于纳米尺度上的粗糙或周期性瓦楞纸表面与完全平坦的表面的值不同。 Wenzel的关系仅将这种差异归因于表面积的几何放大（通过因子$ r _ {\ rm w} $），但是这个想法的有效性是有争议的。我们通过模型计算来阐明此问题的正弦波纹，以$ z {\ rm Wall}（y）=δ\ cos（2πy/λ）$的形式，对于短范围$σ_{\ rm w} $的潜在潜力。当蒸气相是理想的气体时，可以精确计算壁蒸气表面张力的变化，并且对Wenzel方程的校正通常为$σ_{\ rm W}δ/λ^2 $的顺序。对于固定的$ r _ {\ rm w} $和固定$σ_{\ rm w} $，wenzel结果的方法增加了$λ$，可能是非单调的，并且此限制通常仅以$λ/σ_ {\ rm w}> 30 $达到$λ/σ_ {\ rm w}> 30 $。对于非添加二元混合物，使用密度功能理论来确定平面和波纹壁共存阶段的密度曲线，以及相应的表面张力。同样，预测Wenzel的幅度与上述理想气体情况相似的结果。最后，基于接口汉密尔顿概念的粗略简化描述用于沿着相似的线解释相应的仿真结果。当$λ/σ_ {\ rm w} \ gg 1 $，$Δ/λ<1 $ $λ/σ_ {\ rm w} \ gg 1 $时，发现Wenzel的方法通常可以保持。
he contact angle of a liquid droplet on a surface under partial wetting conditions differs for a nanoscopically rough or periodically corrugated surface from its value for a perfectly flat surface. Wenzel's relation attributes this difference simply to the geometric magnification of the surface area (by a factor $r_{\rm w}$), but the validity of this idea is controversial. We elucidate this problem by model calculations for a sinusoidal corrugation of the form $z_{\rm wall}(y) = Δ\cos(2πy/λ)$ , for a potential of short range $σ_{\rm w}$ acting from the wall on the fluid particles. When the vapor phase is an ideal gas, the change of the wall-vapor surface tension can be computed exactly, and corrections to Wenzel's equation are typically of order $σ_{\rm w}Δ/λ^2$. For fixed $r_{\rm w}$ and fixed $σ_{\rm w}$ the approach to Wenzel's result with increasing $λ$ may be nonmonotonic and this limit often is only reached for $λ/σ_{\rm w}>30$. For a non-additive binary mixture, density functional theory is used to work out the density profiles of both coexisting phases both for planar and corrugated walls, as well as the corresponding surface tensions. Again, deviations from Wenzel's results of similar magnitude as in the above ideal gas case are predicted. Finally, a crudely simplified description based on the interface Hamiltonian concept is used to interpret corresponding simulation results along similar lines. Wenzel's approach is found to generally hold when $λ/σ_{\rm w}\gg 1$, $Δ/λ<1$, and conditions avoiding proximity of wetting or filling transitions.
